Energy Balance and Body Composition Chapter 8 Highlight 8 Dr Alisha Rovner NTDT200 Fall 2013 Lecture Objectives Describe energy balance and the consequences of not being in balance List the components of energy expenditure and factors that might influence each Distinguish between body weight and body composition including methods to assess each Identify relationships between body weight and chronic diseases Compare and contrast the diagnoses characteristics and treatments of the different eating disorders Energy Balance People expend energy continuously and eat to refuel Energy balance Energy in energy out maintains weight A shift in balance causes weight changes Energy in energy out gains weight Energy in energy out loses weight 1 pound of fat 3500 kcalories Energy Balance How many extra kCalories would a person have to eat a day to gain 1 lb in a week hint 1 lb 3500 kcal Energy Balance Dietary Guidelines To maintain body weight in a healthy range balance kCalories from foods and beverages with kCalories expended Energy In kCalories Food and beverages provide the energy in part of the energy balance equation How much energy a person receives depends on 1 the composition of foods and beverages 2 amount person eats Energy In Food Intake To achieve energy balance body must meet it s needs without taking in too much or too little energy Appetite is the integrated responses to the sight smell thought or taste of food that initiates or delays eating Energy In Food Intake Hunger Painful sensation caused by a lack of food that initiates food seeking behavior Satiation Feeling of fullness that occurs during a meal tells people to stop eating Satiety Continues to suppress hunger tells people not to start eating again Energy In Food Intake Overriding hunger and satiety Stress eating External cues i e Time of day availability sight taste Environmental influences i e Large portion sizes Cognitive influences i e Comfort foods Disordered eating Energy In Food Intake Sustaining satiation and satiety Nutrient composition Protein is most satiating Low energy density High fiber foods High fat foods strong satiety signals Energy In Food Intake The hypothalamus Control center for eating Integrates messages about energy intake expenditure storage Gastrointestinal hormones Dozens influence appetite control and energy balance Energy Out Thermogenesis generation of heat Can be measured to determine energy expenditure Main categories Basal metabolism Physical activity Food consumption Adaptation Energy Expenditure People expend energy when they are physically active People also expend energy when they are resting quietly Quiet metabolic activities account for large portion of people s energy expenditures Energy Out Basal Metabolism Basal metabolism is the energy needed to maintain life eg body temp lungs inhaling and exhaling air heart beating Accounts for 2 3 of energy expended in a day Basal metabolic rate BMR is the rate at which the body expends energy for lifesustaining activities Energy Out Basal Metabolism Basal metabolic rate BMR Variations from person to person Slowest rate when person sleeping Weight Highest in growing children Lean tissue Resting metabolic rate RMR Factors that Affect the BMR Energy Out Physical Activity Second component of energy output Voluntary movement of skeletal muscles Most variable component of energy expenditure Amount of energy needed Muscle mass Body weight Activity Frequency intensity and duration Table 8 2 p238 Energy Out Thermic Effect of Food TEF TEF is estimation of the energy required to process food digest absorb etc Approximately 10 of energy intake High protein foods high fat foods Meal consumption time frame influences TEF Energy Out Adaptive Thermogenesis Additional energy spend when person has to adapt to dramatically changing circumstances Examples starvation trauma Extra work done by body Amount expended is extremely variable Not included in energy requirement calculations Components of Energy Expenditure Estimating Energy Requirements Gender BMR women lower Growth Groups with adjusted energy requirements eg Pregnant women infant children Age Changes with age Physical activity Levels of intensity for each gender Body composition body size Height Weight Estimating Energy Requirements EER Men 19 yrs and older EER 662 9 53 x age PA x 15 91 x wt x 539 6 x ht Women 19 yrs and older EER 354 6 91 x age PA x 9 36 x wt x 726 x ht Physical Activity PA Factors for EER Equations Sedentary Low active Active Very active Men 1 0 1 11 1 25 1 48 Women 1 0 1 12 1 27 1 45 Physical Activity Typical daily living Plus 30 60 min moderate activity Plus 60 min moderate activity Plus 60 min moderate activity and 60 min vigorous or 120 min moderate activity Defining Healthy Body Weight How much should a person weight How can a person know if his her weight is appropriate for his her height How do you know if your weight puts you at risk for health problems Defining Healthy Body Weight Ideal Not appearance based Perceived body image and actual body size Damaging behaviors Subjective Frequently have little in common with health Tips for Accepting a Healthy Body Weight Defining Healthy Body Weight Body mass index BMI Relative weight for height BMI weight lb x 703 height in 2 BMI weight kg height m 2 Sample BMI calculation A person who is 5 5 and weights 150 lbs BMI 150 lbs 65 in2 x 703 25 A BMI of 25 would classify someone as being overweight Body Mass Index BMI Defining Healthy Body Weight BMI health related classifications Healthy weight 18 5 to 24 9 Overweight 25 29 9 Obese 30 39 9 Not a measure of body composition Limitations eg muscular athletes Distribution of Body Weights in US Adults CDC BMI calculator http www cdc gov healthyweight assessing bmi adult bmi english bmi calculator bmi ca lculator html Body Composition Proportion of muscle bone fat and other tissues that make up a person s total body weight Direct measures in human beings impossible Body composition assessed indirectly based on the following assumption Body weight fat lean tissue Body Fat Males vs Females Body Fat and Its Distribution Needing less body fat Some athletes Needing more body fat Example pregnant women Fat distribution Visceral fat Central obesity Subcutaneous fat Apple and Pear Body Shapes Compared Body Fat and Its Distribution Waist circumference Preferred method for assessing abdominal fat in clinical setting Indicator of fat distribution central obesity Women 35 inches high risk Men 40 inches
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